1. Field of the Invention
The present invention generally concerns a handle for a machinist""s vise.
The present invention particularly concerns handles or machinist""s vises known in the art as xe2x80x9cspeedxe2x80x9d handles and particularly to an economical xe2x80x9cspeedxe2x80x9d handle in which the maximum torque that can be applied to the handle is limited to a preset value so as to limit the clamping force applied by the jaws of the vise to the part being clamped.
2. Description of the Prior Art
The machinist""s vise is a well known devise in the machining art for holding a part being machined on the table of a mill as the milling cutter machines the part. The typical machinist""s vise is bolted onto the table surface of the mill and has a horizontal screw abutting a jaw of the vise and another end on which a handle is mounted and turned such as to clamp the jaws of the vise on the part. The part must be held very firmly to prevent slippage in the vise which could result in ruining the part. However, in numerous instances, particularly when the part has a thin section, the clamping force of the vise can at least temporarily deform the part resulting in a necessity to make adjustments in machining the part to maintain tolerance.
Variations in clamping force from one part to the next can result in variations of the machining dimensions which are greater than the machining tolerance. These variations in clamping force arise from differences between force applied by different operators or even with one operator such as may arise from fatigue.
A number of modifications of the machinist""s vise have been disclosed related to speed opening and closing the vise and applying controlled clamping force.
U.S. Pat. No. 5,192,062 to Berchtold discloses a clamping force adjusting devise for a clamping devise such as a vise which requires a force multiplier attached to a clamping rod.
U.S. Pat. No. 4,738,438 to Horie, et al., discloses a machine vise with a strain gage detector devise enabling the operator to control applied clamping force.
U.S. Pat. No. 4,046,364 discloses a torque limiting devise having a handle portion coupled to the drive screw of the vise through a friction clutch constructed as an integral part of the vise in which frictional force between the clutch disks can be pre adjusted to permit slip when the torque applied to the handle portion exceeds a preset value. The handle is also coupled to the drive screw of the vise by a shrag clutch which is disengaged when the handle is turned in the direction to tighten the vise and is disengaged in the opposite direction so as to provide a positive coupling to retract (loosen) the vise jaws. The construction of the vise requires application of a spanner wrench to adjust the frictional limiting force of the clutch mechanism and the adjustment of the frictional limit force of the clutch mechanism is integral to the base of the vise.
U.S. Pat. No. 5,192,062 for a CLAMPING FORCE ADJUSTING DEVISE FOR A CLAMP DEVISE concerns a clamping force adjusting devise having a hollow housing supported on a movable clamping part of the same, through which housing passes a rotatable and slidable tension rod whose first end can be coupled to a force amplifier and whose second end carries a tension sleeve fixed thereon. The tension sleeve is supported on Belleville springs through a thrust bearing and an intermediate sleeve, the Belleville springs being supported directly in the housing. An adjusting sleeve screws into a fine thread of the housing and has at its end facing the Belleville springs a radially inwardly directed first stop shoulder, which cooperates with a radially outwardly directed second stop shoulder of the intermediate sleeve and/or a spacer ring bearing on the thrust bearing. Belleville springs will be seen to be employed in the preset torquing force vise handle of the present invention.
A prior art patent that is directed to a vise handle fulfilling the same purposes as does the handle of the present invention is U.S. Pat. No. 5,683,077 for a VISE HANDLE WITH TORQUE CONTROL. Indeed, certain of the description regarding the background of vise handles and force-controlled clamping that appears within that patent is within the Description of the Prior Art section of the instant specification. The 5,683,077 patent concerns a handle for a machinists vise configured to preset the maximum clamping force that can be applied to the vise jaws. The handle is constructed such that, in tightening the vise, when a clamping force is applied by the operator to the handle equal to a preset value, a clutching mechanism in the handle will allow the handle to slip without further tightening of the vise. The mechanism includes a ratchet for positive engagement in loosening the vise and for providing a clicking sound that the clutch is slipping and thereby alert the operator that maximum clamping force is being applied.
Accordingly, both the handle of the ""077 patent, and the handle of the present invention, have as their objects the provision of a handle attachable to the drive screw of the standard machinist""s vise for use in turning the drive screw to apply a preset clamping force on a part. This handle is suitably used with the typical (off the shelf) machinist""s vise. The handle can be adjustably preset so as to apply a particular vise to which the handle is currently affixed and used to apply a correspondingly preset clamping force. The handle will elicit a signal to the operator that slipping of the handle is occurring when the torquing force applied to the handle, and the corresponding clamping force of the vise, reaches a preset value.
Further in common with the handle of the ""077 patent, it is an object of the handle of the present invention that the operator can preset a value of force with convenience. It is another object that the maximum force applied to the handle of the vise be more closely controlled than the devises of the prior art. It is still yet another object that the invention have a simple and robust construction, and be economical to build.
The present invention contemplates a compact, effective, reliable and economical torque-limiting handle for a machinist""s vise.
The torque-limiting handle is a slender cylinder in form, being built along an internal shaft. The maximum torque that may be transmitted by the torque-limiting handle is determined by rotation of an external sleeve under force of the fingers. This rotation may readily be accomplished under but even, slight, force regardless that the handle is being preset to transmit low, or high, torque. To facilitate the assumption, and holding, of certain preset torque values, the rotational sleeve is preferably possessed of detents and/or markings, making accurate setting of the sleeve, and the torque-limiting handle, both easy and speedy.
When such torque in a one, vise-tightening, rotational direction as is attempted to be transmitted along the torque-limiting handle reaches the preset limit, the torque-limiting handle will thereafter continue to turn, but will slip in the manner of a ratchet between its driven and driving ends. The slipping handle will make such a sound, and will present such diminished pressure to the hand, as will make clear to the user that the preset torque has been reached, and that the torque-limiting handle is ineffective to transmit any greater torque. The preset maximum tightening torque that is transmitted corresponds to a preset maximum clamping force of the machinist""s vise upon which the torque-limiting handle is being used.
There are no limits on the torque that can be transmitted when the torque-limiting handle is turned in a second, vise-opening, rotational direction. It is thus always possible to positively apply any necessary torque to open the vise, even if such torque must exceed (in a different rotational sense) the preset torque limit.
Such wear, and metal fatigue, as the parts of the torque-limiting handle are subject to does not obviate their function. Being that the handle is not a calibrated torque wrench, but merely an accessory to a machinists vise that, when matched with and adjusted to a particular vise, permits a predetermined clamping force to be reliably repetitively delivered by the vise, the handle should be usable indefinitely without maintenance. When constructed of quality materials, the handle should perform for many decades, and for many hundreds of thousands of tightening and loosening cycles.
1. A Torque-limiting Handle for a Machinist""s Vise
Therefore, in one of its aspects the present invention contemplates a torque-limiting handle for a machinist""s vise having a particular, compact and reliable, torque-imparting mechanism. Namely, the torque-limiting handle has a drive clutch with a distal side for engaging a machinist""s vise and a proximal side having and presenting a plurality of circumferential teeth with ramp surfaces.
A shaft is affixed to the drive clutch and extends distally therefrom.
A pressure clutch, located about the shaft, has and presents at a distal side a complimentary plurality of circumferential teeth suitable to engage the ramp surfaces of the plurality of teeth of the drive clutch.
A mechanical mechanism serves to force the pressure clutch along the direction of the shaft and into the drive clutch. This forcing is realized at a variably predetermined pressure.
Finally, a coupler of an external torquing forcexe2x80x94such as may be and most commonly is provided by the human handxe2x80x94serves to rotate the pressure clutch.
By this simple structure the drive torque applied to the pressure clutch by the coupler produces a regular repeatable increase in angular displacement of the drive clutch until, a preset torque being reached, the plurality of teeth of the drive clutch will ramp over and snap free of the teeth of the pressure clutch, and no further torquing of the drive clutch can be realized. The jaws of the machinist""s vise engaged by the drive clutch can thus be tightened to an adjustably predetermined extent, and no tighter.
The mechanical mechanism serves preferably consists of a number of spring, or Belleville, washers affixed about the shaft at the proximal end thereof. These washers pressure against a main body fitting circumferentially about the shaft so as to place this main body in variably predetermined extension from an adjustment body fitting circumferentially about the shaft and abutting against the pressure clutch. The adjustment of the variably predetermined extension of the main body from the adjustment body, and vice versa, determines how strongly the pressure force of the plurality of spring washers is transmitted to the pressure clutch. The pressure clutch is thus forced into the drive clutch at the variably predetermined pressure.
There may optionally be included detentes between the main body and the adjustment body for holding a variably selected screwed separation therebetween.
The coupler most commonly consists of a handle mount rotationally linked to the pressure clutch, and a handle, graspable by the hand, affixed to the handle mount for imparting rotation thereto. This handle is preferably pivotally affixed to the handle mount.
2. A Mechanism for Engaging the Vise Shaft of a Vise to Impart a Predetermined Torque
In another of its aspects, the present invention can be considered to be embodied in a mechanism for engaging the vise shaft of a vise to impart a predetermined torque to the shaft, thereby to develop a correspondingly predetermined force between jaws of the vise.
The preferred mechanism has a drive clutch having (1) a distal end coupling that engages to the vise shaft of a vise and (2) a proximal end multiple tooth inclined plane.
A drive shaft is affixed to the drive clutch and extends proximally therefrom.
A pressure clutch, fitted about the shaft, has a distal end multiple tooth inclined plane complimentary to, and mating with, the multiple tooth inclined plane of the drive clutch. This mating is so that a given rotational torque in a one rotational direction applied to the pressure clutch about the shaft will, in accordance with the extent to which the distal end of the pressure clutch is held pressured to the proximal end of the drive clutch, produce a correspondingly associated angular rotation of the drive clutch. This angular rotation of the drive clutch serves to tighten the vise for a range of applied torques and associated angular rotations until, at a preset torque and a corresponding maximum angular rotation of the drive clutch and a corresponding maximum tightening of the vise, the pressure clutch will thereafter slip relative to the drive clutch.
Meanwhile, rotational torque in an opposite rotational direction applied to the pressure clutch will invariably produce a correspondingly associated angular rotation of the drive clutch as serves to open the vise.
An adjustment mechanism is located proximally of the pressure clutch about the drive shaft, and is rotatably affixed to the pressure clutch. This adjustment mechanism serves to (1) force at a variably predetermined force the pressure clutch into pressured contact with the drive clutch while (2) imparting rotation to the pressure clutch. A handle graspable by the human hand is normally connected, and serves to impart rotation, to the adjustment mechanism.
In detail, the adjustment mechanism preferably consists of three major parts, all arrayed about a central shaft.
1) A generally cylindrical adjustment body is centered about the shaft, with its distal end against a proximal end of the pressure clutch, and with internal screw threads at its proximal end.
2) A generally cylindrical main body, centered about the shaft proximally of the adjustment body, has an extension passing through the adjustment body to rotationally engage the pressure clutch, a distal end shoulder against a proximal end of the adjustment body, distal end external screw threads threadingly engaging the screw threads of the adjustment body, and a proximal end region connecting the handle.
3) A plurality of spring washers are arrayed centered about the shaft distally of the main body. A stop at the proximal end of the shaft holds the plurality of spring washers upon the shaft.
By this construction a threading engagement of the adjustment body and the main body to a variable extent variably compresses the spring washers, transmitting the variable compression force thereof along the axis of the shaft to the pressure clutch, and forcing the pressure clutch into variable compression with the drive clutch.
The adjustment mechanism preferably further includes detents between the adjustment body and the main body tending to hold both bodies at a manually preset rotation angle of threading engagement one body relative to the other. This manually present rotation angle determines the variable compression of the spring washers which, as transmitted along the axis of the shaft to the pressure clutch, forces the pressure clutch into variable compression with the drive clutch.
These and other aspects and attributes of the present invention will become increasingly clear upon reference to the following drawings and accompanying specification.